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Urinary pathogenicity of Proteus mirabilis strains isolated from faeces or urine
Abstract:
Urinary and faecal isolates of Proteus mirabilis were studied with respect to a number of bacterial properties as possible virulence factors in the pathogenesis of urinary tract infections: experimental virulence in a mouse model, haemolysin production, haemagglutinating properties, hydrophobicity of the bacterial surface, sensitivity to the bactericidal effect of human serum, serotype and cell invasiveness. Urinary isolates were slightly more virulent than faecal isolates in the mouse model. No other significant differences were found between both groups. So urinary strains seem to be selected from the faecal reservoir mainly on the basis of their prevalence in the faeces and not on the basis of the possession of particular virulence factors.
Insights
Proteus mirabilis strains causing urinary tract infections were studied. Urinary isolates showed slightly higher virulence, but lacked specific virulence factors, suggesting selection from the fecal reservoir based on prevalence rather than specific traits.
Area of Science:
- Microbiology
- Infectious Diseases
- Bacterial Pathogenesis
Background:
- Proteus mirabilis is a common cause of urinary tract infections (UTIs).
- Virulence factors contributing to UTI pathogenesis by P. mirabilis are not fully understood.
- Understanding bacterial selection mechanisms is crucial for infection control.
Purpose of the Study:
- To investigate potential virulence factors in urinary and faecal isolates of Proteus mirabilis.
- To compare the virulence of urinary and faecal P. mirabilis strains in a mouse model.
- To determine if specific bacterial properties differentiate UTI-causing strains from commensal isolates.
Main Methods:
- Comparison of urinary and faecal P. mirabilis isolates.
- Assessment of experimental virulence in a mouse model.
- Evaluation of bacterial properties: haemolysin production, haemagglutination, surface hydrophobicity, serum sensitivity, serotyping, and cell invasiveness.
Main Results:
- Urinary P. mirabilis isolates exhibited slightly higher experimental virulence in mice compared to faecal isolates.
- No significant differences were observed in other tested virulence factors (haemolysin, haemagglutination, hydrophobicity, serum sensitivity, serotype, invasiveness) between urinary and faecal groups.
- The prevalence of strains in faeces appears to be a more significant factor in UTI causation than possession of specific virulence factors.
Conclusions:
- The selection of P. mirabilis strains for causing UTIs from the faecal reservoir may be primarily driven by their abundance in faeces.
- Specific virulence factors do not appear to be the main differentiating characteristic for urinary strains.
- Further research could explore other host-related or environmental factors influencing UTI development.